We could see you in the gas tank later, alligator

Production of biodiesel as an alternative to fossil fuels is on the rise in the United States, and one reason, proponents say, is that it can be made from a long list of raw materials.

“Biodiesel is made from all sorts of fats and oils,” said Ben Evans of the National Biodiesel Board, a trade group based in Washington. While oils made from soybeans, rapeseed and other plants account for at least 85 percent of U.S. production — a record 1.8 billion gallons in 2013 — “any type of animal fat that's properly processed” will work as well, he said.

As if to demonstrate Evans' point, a team of chemists and engineers at the University of Louisiana, Lafayette, has spent the last several years investigating the possibility of producing biodiesel from an unusual source: alligators.

Mincing and microwaving chunks of the reptiles' fat in their laboratory, the researchers found it could be converted into fuel of sufficient quality that, like biodiesel from other sources, could be blended with conventional petroleum-based diesel for use in vehicles and equipment.

The team recognized that the amount of alligator fat available for conversion to biodiesel was dwarfed by other sources, such as beef and chicken fat, and now is working on developing more efficient production techniques that would be applicable to any animal-based biodiesel.

“We're trying to work on the exact conditions now, to better understand the kinetics,” said August A. Gallo, a chemistry professor at the university and a leader of the research team.

At first, Gallo said, he and the other researchers, including Thomas Junk, a chemist, and Rakesh K. Bajpai, a chemical engineer, did not intend to make biodiesel from alligators. The alligators — or more precisely, alligator farmers — came to them.

“Some local entrepreneurs in Lafayette do a lot of alligator farming,” he said.

The reptiles are slaughtered for their hides and for food, and alligator meat is a common sight on menus in parts of the South. But the farmers had to pay to discard the rest of the animals, including the fat, which Gallo estimated makes up about 10 percent of an alligator's weight.

“They have this enormous amount of waste,” he said. “And they didn't know what to do with it.”

Gallo said he did not know much about alligator fat when the project started. But that changed when the farmers began supplying the researchers with 50-pound frozen blocks of it.

The researchers made biodiesel in small batches in the lab, cutting up the fat tissue first and heating it in a microwave to remove most of the moisture. Heating this rendered fat with an alkaline compound and methanol — a common production method — resulted in the chained hydrocarbons that are characteristic of biodiesel.

Analysis showed that the gator-based product met almost all of the technical specifications for fuel-grade biodiesel. Conforming it fully would require only slight modifications to the process, Gallo said.

Alligator fat “was a little bit more unsaturated than we thought it would be,” he added. That gave it a lower melting point and meant that the resulting biodiesel would flow better in lower temperatures. “But in other ways, it hurts the performance,” Gallo said. “So it's a mixed bag.”

The researchers now are working on developing a continuous-flow process that would produce more biodiesel much faster and could be used with any animal fat. But the process is still at the laboratory stage, Gallo said.

By some estimates, about 15 million pounds of alligator fat is discarded each year. While that may seem like a lot, it is little compared with the amount of wasted fat from the beef, pork and chicken industries, and from renderers who produce lower-quality fat from dead farm animals and other sources.

Still, because alligator fat is available at little or no cost, even a relatively small biodiesel operation could be viable, Gallo said. Animal fats are byproducts, so using them would help address concerns about growing soy and other crops for biodiesel when they might better be used for food. As byproducts, the fats are also usually less expensive than vegetable oils, said Jon Van Gerpen, an engineering professor at the University of Idaho.

“With biodiesel, we're looking for every source we can to make it price competitive,” he said.

“The question for them is, is animal fat enough cheaper than vegetable oil that I can afford to put in this equipment?” he said. “Right now it seems there is good money to be made with plant oils.”